You can tell the medical students at your local teaching hospital. They're the ones with the short lab coats and the pockets bulging with small paper-back books.
For those who are in training to become a Doctor a premium is placed on easily-accessible, highly accurate and important information. I remember going through my clinical rotations and thinking that I needed a "pocket" book for every medical rotation to supplement my massive 20-pound, $100 texts while I was on the wards and in the clinic.
Early into my OB/GYN Residency I got the hot scoop - THIS is the book to keep in your lab-coat if you're practicing OB/GYN. By the time I was a chief resident this book had saved me time and heartache and saved my patients from my blunders over and over. Like all "pocket" texts, this one doesn't contain lengthy discussions. But it DOES contain what you need to get through that night on OB/GYN call. And the next one.... and the next.
The treatment for Pelvic Inflammatory Disease (and hundreds of other common clinical situations)- before it's burned into your brain it's right here at your fingertips. It even gives you concise "go-by's" for how to dictate your operative reports for the most common OB/GYN surgeries.
Since I got my first one a decade ago I've never NOT had a copy of this in my lab coat. I use it infrequently now, but when young trainees seem to need a push towards a clue - I push them towards this little gem.